1. Field of the Invention
The present invention relates to an electric charging system and an electric vehicle, and, in particular, to a technology that prevents a weld failure or fusion failure of a relay provided to an electric vehicle.
2. Description of the Related Art
In recent years, electric vehicles that are equipped with an electric motor for propulsion have been under development. When an electric storage device such as a battery that is installed at the electric vehicle is charged, a power feed connector extending from an external electric charger is connected to a power receiving connector of the electric vehicle. Furthermore, in the field of hybrid electric vehicles that are equipped with an engine and an electric motor for propulsion, an electric vehicle of the so-called plug-in system, in which an electric storage device is charged with an external electric charger, is under development.
Since a terminal voltage of the electric storage device is applied to the power receiving connector provided to the electric vehicle, it is necessary to ensure safety during a charging operation in which the power receiving connector is exposed. Thus, a relay is provided to a power supply line that connects the electric storage device and the power receiving connector. When the charging operation is not performed, the relay is disconnected, thereby preventing the terminal voltage from being applied to the power receiving connector.
Since a large current is supplied during charging to the relay thus provided on the power supply line, a weld failure or fusion failure may occur. Accordingly, an electric charging system is suggested that switches the relay to a disconnection state after charging is complete as well as monitors a voltage change due to the relay disconnection (see, for example, Japanese Unexamined Patent Application Publication No. 2010-238576). By using such an electric charging system, it is possible to detect a weld failure of the relay.